The Terminal 117 cleanup site (T-117), located on the west bank of the Lower Duwamish Waterway in South Park, is a joint cleanup project by the Port of Seattle and City of Seattle. This site was identified for cleanup because the upland property, river bank and sediments, and parts of the adjacent yards and streets have high concentrations of PCBs (polychlorinated biphenyls), dioxin/furans and other contaminants. T-117 is designated as an Early Action Area (EAA) as part of the Lower Duwamish Waterway Superfund Site listed by the U.S. Environmental Protection Agency (EPA) under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA).

In fall of 2010, EPA issued the final removal Action Memorandum for the T-117 site based on the findings in the project's cleanup plan (EE/CA). The Action Memorandum identifies a plan to remove upland soil and river sediment to reduce PCBs and other contaminants to levels that will protect the river environment and reduce health risks to people. Cleanup design is now complete and cleanup construction is scheduled to begin in June 2013 and finish around June 2014. Residential yards cleanup was completed in February 2013. Uplands/sediments cleanup will begin June 2013.